In the field of photography, a photographer is often confronted with scenes that have extreme imaging properties, such as high dynamic range and unusual color balance. Dynamic range typically refers to a ratio between maximum and minimum values of physical measurement, and in photography specifically refers to a ratio of luminance values. Color balance typically refers to a comparative ratio of intensities of colors in an image.
Examples of scenes with extremes in imaging properties include scenes with high dynamic range or unusual color balance. In some cases, such a scene may have multiple different regions, each with different brightness levels or a different color balance. For example, a scene might include a first region depicting bright day light and a second region depicting dark shadow. In this situation, the first region depicting bright day light has a different brightness level and a different color balance than the second region depicting dark shadow.
Furthermore, such scenes typically include transitions between the multiple different regions. For example, a scene including regions with well-defined edges, such as a scene including a bright window in a dark room, has an abrupt transition in imaging properties. On the other hand, a scene including regions without well-defined edges, such as a scene including clouds in the sky, has a more smooth transition in imaging properties.
When confronted with such a scene, the photographer is often compelled to capture many images of the scene, each with different exposure settings, such as shutter speed and/or color balance. Then in post-capture image processing, the photographer combines the images into an acceptable rendition of the scene. This acceptable rendition may not be achievable due to loss of information during capture, such as saturated channels, that cannot be easily estimated or reconstructed. Moreover, the photographer is often compelled to use post-capture image processing tools in order to achieve an accurate or desired transition between the multiple regions of the scene. Such post-capture image processing tools are often cumbersome and inflexible.